Honeywell V4073A

[scadding]

I realise that this is a common fault but I would appreciate some advice before trying to rectify it. Last night I switched the CH on for the first time but none of the radiators warmed up. I manually moved the lever on the valve and everything warmed nicely. Unfortunately having returned the lever to auto, the valve will not close when either the timer is set to HW only or the thermostat is switched off. I'm not sure if the problem is likely to be a stiff spindle, a failed motor or another failure within the actuator. I tried to remove the unit last night but realised that one of the two fixing screws was actually unscrewing the brass lug that holds the brass plate in position and also receives the actuator fixing screw. My questions are:

1) If I continue to unscrew the brass lug until fully removed would you expect the unit to start leaking? At the moment I cant free the fixing screw that holds the actuator in place from the brass lug...
2) What is the most likely cause of the unit no longer working correctly?

Thanks in advance........

 

[doitall]

If you don't have a dimple on the silver case you can't take the actuator off without draining the system down.

If it's that old change the whole valve

 

[scadding]

Sorry I should have confirmed that the actuator DOES have the dimple on the case...

 

[doitall]

Sorry I should have confirmed that the actuator DOES have the dimple on the case...

Then should only have two screws holding the actuator on.

Can you post a pic, it may have been converted.

 

[scadding]

Yes that appears likely as there is a brass plate attached to the body of the valve. The plate is fixed by using 4 brass threaded lugs, 2 of which have nipples on one end and 2 of which have a thread that receives the two actuator fixing screws. The problem is that as I undo one of the actuator screws, the brass lug that it screws into is also turning and therefore unscrewing itself from the brass plate and valve face. I'm therefore worried that if I continue to unscrew the brass lug the brass plate (conversion plate?) will start to allow water past.... is this probable??

 

[doitall]

Best rule with plumbing is "Anything is Possible".

Going on the age it would be best to drain down and fit a new valve complete.

Make a note of which port goes where so you fit it the right way round.

The wires you can snip off after you isolate the electric then swap them one at a time.